The output transistors can be BC548 and BC558. The circuit is from a 1975 documentation showing a frequency response from 90 Hz to 12.5 kHz.
This circuit is intended for underwater communications. Of course, the critical point is the...
This circuit was found in an Electronic Design from the 90s. The circuit uses a type J...
This simple windscreen wiper interval was found in old American documentation. The relay must have...